Synthesis And Uranium Adsorption Characterization Of Graphene And Graphene-based Materials

Graphene, a one-atom thick sheet of hexagonally arrayed sp2bonded carbon atoms, hasattracted wide interest for its unusual electronic, mechanical, and thermal properties. It is anew member of the carbon material family. Graphene composite materials own both excellentperformance of graphene and characteristics of other materials, so it has been widelyresearched. This paper mainly focuses on the preparation of graphene. Moreover the uraniumadsorption of graphene based matrtials was studyed. The specific work introduced as follows:We put forward a green, rapid method of preparation high-quality graphene. That isreduction of graphite oxide by Zinc powder. XRD, FT-IR, Raman, TGA and XPS wereimployed to test the structure and quality of the as-obtained graphene. The results show thatmost of the oxygen functional groups of graphite oxide (GO) were removed and the degree ofgraphitization is improved, the thermodynamic stability was also enhanced greatly. In addition,the defects left by removing of the oxygen function groups have been repaired with theextension of reaction time. The possible reaction mechanism was also speculated.Grephene having highly dispersibility in water was successfully synthesised, usingEDTA-2Na as a chemical reduction agent. XRD, FT-IR, Raman, TGA and XPS was used totest the prepared graphene. The results show that most of the oxygen functional groups in GOwas removed, and the defects have been repaired. TGA test indicates that the graphene hasgood thermal stability. Through the TEM, SEM and BET, we can find that the flower-shapeda graphene has high surface area. The results of UV-vis show graphene has good dispersibilityin water. The optimum uranium adsorption conditions is the amount of adsorbent is0.04g, thereaction time is4h, the pH is6and the temperature is25℃. Under these conditions themaximum adsorption capacity is49.90mg/g. The adsorption processt fit quasi secondaryadsorption dynamics model and D-R adsorption isotherm. The results of thermodynamicshow ΔH=-18.49KJ/mol, indicated an exothermic process. ΔG<0indicate that the adsorptionreaction is a spontaneous process. ΔS<0confirms the depressed randomness.The magnetic graphene composites were prepared and uranium adsorption wasinvestigated. The optimum condition was as follow: the amount of adsorbent is0.06g,reaction time is300min, the pH of solution is6and the temperature is25℃. Under these conditions the maximum adsorption capacity is47.70mg/g. The adsorption processt fit forquasi secondary adsorption dynamics model and D-R adsorption isotherm. The results ofthermodynamic parameters is ΔH=-76.1KJ/mol, indicated an exothermic process. ΔS <0andΔG <0indicate that reflect a spontaneous process and a depressed randomness at thesolid-solution interface during adsorption.